[Duration of oral anticoagulant therapy in deep venous thrombosis of the lower limbs].

The optimal duration of oral anticoagulant therapy is a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. Recent data suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of deep vein thrombosis (DVT) and the presence of risk factors. A six-week treatment for patients with isolated calf DVT is sufficient. For proximal DVT and/or pulmonary embolism, a short anticoagulant course seems sufficient in patients with temporary risk factors (three months) and a longer anticoagulant course (six months at least) is recommended for cases with permanent risk factors or idiopathic DVT. The inherited or acquired hypercoagulable states can be divides into those that are common and associated with a modest risk of recurrence (i.e. isolated factor V Leiden or G20210A prothrombin gene) and those are uncommon but associated with a high risk of recurrence (i.e. antithrombin, protein C or S deficiencies and anticardiolipin antibodies). Thus, the presence of one of these last abnormalities favours more prolonged anticoagulant therapy. For the high-risk of recurrence patients, there is a paucity of evidence based medicine particularly for patients with biological thrombophilia, and randomised controlled trials in this population are required. An assessment of low- or fixed-dose oral anticoagulation is also necessary in order to reduce the bleeding risk.